From cd77713255a19db6f5eb0f897a831bdcbacbff95 Mon Sep 17 00:00:00 2001
From: Ari Sundholm <megari@iki.fi>
Date: Thu, 5 Nov 2020 18:39:22 +0200
Subject: [PATCH] ulibSD/spi_io.[ch]: Add function to write a single byte over
 SPI.

Additionally, fix the misleading documentation for SPI_RW().
The new function, SPI_WW() follows the same naming logic, for better
or worse.
---
 software/sys_controller/ulibSD/spi_io.c |  4 ++++
 software/sys_controller/ulibSD/spi_io.h | 10 ++++++++--
 2 files changed, 12 insertions(+), 2 deletions(-)

diff --git a/software/sys_controller/ulibSD/spi_io.c b/software/sys_controller/ulibSD/spi_io.c
index c6f1afd..2e3cd7b 100644
--- a/software/sys_controller/ulibSD/spi_io.c
+++ b/software/sys_controller/ulibSD/spi_io.c
@@ -23,6 +23,10 @@ void SPI_R(BYTE *rd, int len) {
     SPI_read(SD_SPI_BASE, rd, len);
 }
 
+void SPI_WW(BYTE d) {
+    SPI_W(&d, 1);
+}
+
 BYTE SPI_RW (BYTE d) {
     BYTE w;
     SPI_R(&w, 1);
diff --git a/software/sys_controller/ulibSD/spi_io.h b/software/sys_controller/ulibSD/spi_io.h
index e2d0615..b490469 100644
--- a/software/sys_controller/ulibSD/spi_io.h
+++ b/software/sys_controller/ulibSD/spi_io.h
@@ -36,12 +36,18 @@ void SPI_R (BYTE *rd, int len);
 void SPI_W (BYTE *wd, int len);
 
 /**
-    \brief Read/Write a single byte.
-    \param d Byte to send.
+    \brief Read a single byte.
+    \param d Byte. Ignored.
     \return Byte that arrived.
  */
 BYTE SPI_RW (BYTE d);
 
+/**
+    \brief Write a single byte.
+    \param d Byte to write.
+ */
+void SPI_WW(BYTE d);
+
 /**
     \brief Flush of SPI buffer.
  */